This invention relates to nut cracking apparatus and in particular to a machine for cracking nuts of different size in a cyclical operation. The apparatus includes a feed mechanism for metering the supply of nuts to the cracking machine during each cycle of operation.
The nut cracking apparatus of this invention relates to the Nut Shelling Machine, U.S. Pat. No. 5,115,733, issued May 26, 1992, the Nut Shelling Machine, U.S. Pat. No. 4,793,248, issued Dec. 27, 1988 and the Nut Cracking Machine, U.S. Pat. No. 5,247,879, issued Sep. 28, 1993. Each of the prior art machines was primarily directed to cracking the difficult macadamia nut which has a thick shell and varies in size. The feed mechanism of U.S. Pat. No. 4,793,248 that meters the feeding of nuts to the cracking machine and the vibratory feed mechanism of U.S. Pat. No. 5,115,733 that queues the nuts are combined in the feed mechanism of this invention. The primary novelty and uniqueness, however, resides in the cracking machine which differs substantially from those of the cited prior art references.
It has been found that to crack the difficult macadamia nut with minimal damage to the kernel both a compressive force and a shear force is required. The various mechanisms that have been devised to accomplish this effect have been relatively complex and require continuous adjustment to accommodate nuts of different size. A maximum product value can be obtained from the cracked nut where the nut remains whole and suffers minimal damage during the cracking process. It is speculated that the shear action provides a slight roll to the nut and capitalizes on local fracture zones that permit cracking with minimal force. Power requirements to operate the cracking machine and the potential for crushing the kernel are substantially reduced by the dynamic effect of combining direct force with a shear component.
The nut cracking apparatus of this invention may be used for a variety of other nuts and the use of the macadamia nut is primarily used to demonstrate the efficiency of the machine with an appropriate exemplar nut. However, it is to be understood that the macadamia is one of the most difficult of all nuts to shell and commands a substantial premium for minimally damaged kernels.